Typically, a solid oxide fuel cell (SOFC) employs an electrolyte of ion-conductive oxide such as stabilized zirconia. The electrolyte is interposed between an anode and a cathode to form an electrolyte electrode assembly (MEA). The electrolyte electrode assembly is interposed between separators (bipolar plates). In use, normally, predetermined numbers of the electrolyte electrode assemblies and the separators are stacked together to form a fuel cell stack.
In the fuel cell stack, since the electrolyte electrode assemblies and the separators are stacked alternately in the vertical direction, in particular, the entire weight of the fuel cell is directly applied to the fuel cell (electrolyte electrode assemblies and separators) provided at the lowermost position of the fuel cell stack. Therefore, the fuel cell at the lowermost position of the fuel cell stack tends to be damaged easily.
In this regard, for example, structure disclosed in Japanese Laid-Open Patent Publication No. 2002-280052 is known. As shown in FIG. 10, according to the disclosure of Japanese Laid-Open Patent Publication No. 2002-280052, a fuel cell 1 is formed by stacking power generation cells 2 and separators 3 alternately in a vertical direction. A single fuel end plate 4 is stacked at the end of the fuel cell 1 at the lowermost position, and a single air end plate 5 is stacked at the end of the fuel cell 1 at the uppermost position.
The fuel cell 1 is placed on a base plate 6, and connection members 7 are inserted into four corners. Screw holes 8 are formed at four corners of the separator 3, at four corners of the air end plate 5, and at four corners of the fuel end plate 4. Screws 9 are screwed into the screw holes 8, and surface to surface contact is applied between tip ends of the screws 9 and the connection members 7.
In the structure, it is possible to maintain the load applied to the power generation cells 2 at the lower positions of the fuel cell 1 to be substantially the same as the load applied to the other power generation cells 2. According to the disclosure, the load is not applied to the power generation cells 2 excessively, and damages of the power generation cells 2 can be prevented.